1. Field of the Invention
The present invention relates to an unlubricated bearing structure supporting a rocking arm to be swingable and to an IC socket using the same.
2. Related Art
FIG. 9 shows a conventional unlubricated bearing structure 100 of the type mentioned above. The unlubricated bearing structure 100 shown in FIG. 9 includes a bearing mount member 102 having an axial bearing hole 103, a cylindrical bush 101 which has an outer peripheral portion and which is pushed into the bearing hole 103, and a support shaft 104 which is fitted into the cylindrical bush 101 so that a clearance 105 exists between an inner peripheral portion of the cylindrical bush 101 and an outer peripheral portion of the support shaft 104 to thereby support the support shaft 104 to be rotatable by the bush 101 fixed to the bearing mount member 102 (refer to, for example, Japanese Patent Laid-open Publication No. SHO 62-242129, and JIS Machine Engineering Handbook (new edition), published on Mar. 15, 1968, pp. 8-319 to 8-324)
Such an unlubricated bearing structure 100 is applicable to be disposed between relatively rotatable two members of a device to which a lubricating agent (lubricant) is not usable (such as electrical testing device of an IC package requiring an insulating property).
However, such unlubricated bearing structure 100 has provided the following defects.
That is, as shown in FIGS. 10A and 10B, in which the conventional unlubricated bearing structure 100 is applied to a central portion of the rocking (swinging) motion of the rocking arm 106, and one end side of the rocking arm 106 corresponds to the bearing mount portion 102 shown in FIG. 9.
With the conventional bearing structure 100 shown in FIG. 10A and FIG. 10B, when a force F1 other than self-weight pressing the rocking arm 106 toward the center of rocking motion acts, the support shaft 104 made of metal (stainless steel) slidably contacts the cylindrical bush 101, also made of metal (stainless steel), which results in causing of problem of significant wearing of the support shaft 104 as represented by oblique lines in FIG. 10B and the rocking arm is hence hardly driven or operated smoothly and easily, thus being defective and disadvantageous.